Processes for the preparation of an insoluble biomass gel are disclosed involving:
(a) mixing ground agricultural materials and hexane to produce de-oiled agricultural materials,
(b) treating the de-oiled agricultural materials with thermostable α-amylase to produce de-oiled and de-starched agricultural materials,
(c) mixing alkali with the de-oiled and de-starched agricultural materials to produce a first residue,
(d) mixing hydrogen peroxide with the first residue to form a second residue, and
(e) mixing the second residue in water and collecting an insoluble material which is an insoluble biomass gel.
Agricultural processing byproducts (e.g., sorghum bran, corn bran, corn fiber, rice fiber, rice hulls, pea fiber, barley hulls, oat hulls, soybean hulls, sugar cane bagasse, carrot pomace, psyllium husk, etc.) contain numerous components that could be valuable co-products if they could be economically isolated. Agricultural residues (e.g., corn stover, wheat straw, rice straw, barley straw etc.,) and energy crops (e.g., sorghum bagasse, biomass sorghum, switchgrass, miscanthus, etc.) may also be abundant and inexpensive sources for many valuable coproducts. Such lignocellulosic materials rich in lignocellulose are abundant and renewable biological resources. These lignocellulosic materials are natural composites consisting of three main polymeric components: cellulose, hemicellulose, and lignin, as well as other minor components such as extractives (e.g., phenolics, lipids, etc.), pectin, or protein (Zhang, Y.-H. P., and L. R. Lynd, Biotechnol. Bioeng., 88: 797-824 (2004); Fengel, D., and G. Wegener, Wood: Chemistry, Ultrastructure, Reactions; Walter de Gruyter & Co., Berlin, 1984). Lignocellulosic byproducts are the source of many valuable bio-based products which can be used in several industries. Fibers from lignocellulosic sources have various applications, such as building materials, particle board, human food, animal feed, cosmetics, medicine and many other applications (Reddy, N., and Y. Yang, Trends in Biotechnology, 23: 22-27 (2005)). It is becoming important to develop consumer products from the above mentioned renewable resources. The isolation of cellulose suitable for human consumption from agricultural processing byproducts (e.g., soy hulls, sugar beet pulps, pea hulls, corn bran, etc.) has been reported (U.S. Pat. Nos. 4,486,459; 5,057,334). Corn fiber/bran, a renewable resource available in huge quantities, can be a good source of valuable consumer products. Corn fiber makes up about 5 to 10 wt. % portion of the total weight of the corn kernel. It is made up of a number of valuable components which if extracted economically can be commercially valuable. Corn fiber consists primarily of residual starch (10 to 20 wt. %), hemicelluloses (40 to 50 wt. %), cellulose (15 to 25 wt. %), phenolic compounds (3 to 5 wt. %), protein (5 to 10 wt %), and some oils (Wolf, M. J., et al., Cereal Chemistry, 30, 451-470 (1953); Chanliaud, E., et al., J. Cereal Science, 21:195-203 (1995)). The variations in the fiber composition are believed to be due to corn plant variety and growth conditions as well as isolation methods used.
After removing the commercially valuable component “hemicelluloses” from, for example, corn fiber, we isolated and purified the insoluble residue. Based on our studies, this residue, called “Insoluble Biomass Gel” (IBG), has a unique water holding capacity and could be used, for example, as a food bulking agent and thickener.